
Originally Posted by
lph
So I was thinking that maybe we want to give drive-by encouragement mostly for our own sakes, because we'd rather be thought of as cyclists than as drivers...

I think you hit the nail on the head with this one. I think it is more for our own benefit than the person on the bike. Kind of gives us a sense of belonging.
As we must account for every idle word, so must we account for every idle silence." ~Benjamin Franklin